Users appreciate WP-Optimize for its comprehensive features such as database cleaning, caching, image compression, and minifying site code. They find it boosts website speed and performance effectively and like its simplicity and intuitive interface. It's seen as a must-have for users of themes like Divi and Elementor. However, some users faced issues with the plugin interfering with other site functionalities, like calendars or sliders, and a few reported problems with image compression not working or the tool causing page delays. Despite these issues, the general sentiment is positive, with many considering it a reliable and efficient optimization tool.